您正在看的SQLserver教程是:MD5算法的T-SQL實現(FOR SQL2000)。
/*****************************************************************************
* Name: T-SQL MD5算法實現
* Author: Rambo Qian
* Create Date: 2003-04-10
* Last ModifIEd by: Rambo Qian
* Last Update Date: 2003-04-16
* Version: V1.0.00
*****************************************************************************/
GO
IF EXISTS(SELECT * FROM dbo.sysobjects WHERE id = OBJECT_ID(N''''[dbo].[MD5_m_OnBits]'''') AND xtype IN(N''''FN'''', N''''IF'''', N''''TF''''))
DROP FUNCTION [dbo].[MD5_m_OnBits]
GO
/*****************************************************************************
* Name: MD5_m_OnBits
* Description: 常數組
*****************************************************************************/
CREATE FUNCTION dbo.MD5_m_OnBits(
@i TINYINT
)
RETURNS INT
WITH ENCRYPTION
AS
BEGIN
DECLARE @iRes INT
SELECT @iRes =
CASE @i
WHEN 0 THEN 1 -- 00000000000000000000000000000001
WHEN 1 THEN 3 -- 00000000000000000000000000000011
WHEN 2 THEN 7 -- 00000000000000000000000000000111
WHEN 3 THEN 15 -- 00000000000000000000000000001111
WHEN 4 THEN 31 -- 00000000000000000000000000011111
WHEN 5 THEN 63 -- 00000000000000000000000000111111
WHEN 6 THEN 127 -- 00000000000000000000000001111111
WHEN 7 THEN 255 -- 00000000000000000000000011111111
WHEN 8 THEN 511 -- 00000000000000000000000111111111
WHEN 9 THEN 1023 -- 00000000000000000000001111111111
WHEN 10 THEN 2047 -- 00000000000000000000011111111111
WHEN 11 THEN 4095 -- 00000000000000000000111111111111
WHEN 12 THEN 8191 -- 00000000000000000001111111111111
WHEN 13 THEN 16383 -- 00000000000000000011111111111111
WHEN 14 THEN 32767 -- 00000000000000000111111111111111
WHEN 15 THEN 65535 -- 00000000000000001111111111111111
WHEN 16 THEN 131071 --
